1. Field of the Invention
The present invention relates to a display device and a finder device having an edge-light-type backlight.
2. Description Related to the Prior Art
Liquid crystal display devices include a liquid crystal panel and a backlight. The backlight is disposed on the rear surface of the liquid crystal panel, and illuminates the liquid crystal panel with light. Recently, in order to decrease a thickness of the liquid crystal display device, edge-light-type backlights have been widely used. The edge-light-type backlight includes a light guide and a plurality of light sources disposed along sides of the light guide. Light, which is emitted from the light sources, is incident into the light guide, and is emitted in a planar shape from the light guide toward the light crystal panel.
One or a plurality of light guides is provided in the liquid crystal panel. The amount of light of the light sources is controlled for each light guide. Specifically, processing of controlling the amount of light of the light sources so as to decrease luminances of the light guides corresponding to a dark part of a video and correcting a luminance of a video signal in accordance with the light amount control may be performed (refer to US2012/0230056A, which corresponds to WO2011/042999A). As a result, in the dark part of the video, a contrast, at which a luminance of a displayed image is substantially constant, is improved, and low power consumption of the backlight is achieved. This is called dimming control. In particular, separately controlling the luminances of the plurality of light guides is called local dimming control.
In US2012/0230056A, a plurality of light sources (hereinafter referred to as a light source group) provided for one light guide are connected in series or in parallel with each other, and are periodically driven on the basis of a pulse width modulation (PWM) dimming signal. By changing the pulse width of the PWM dimming signal (that is, changing a duty ratio), the amount of light of the light source group is controlled.
Further, there is a known liquid crystal display device that has an edge-light-type backlight and is used as a display device within an electronic viewfinder device mounted on an imaging apparatus such as a digital camera (refer to JP2013-009160A).
In the display device described in US2012/0230056A, in order to decrease the luminance of the light guide, the pulse width of the PWM dimming signal supplied to the light source group provided for the light guide is set to be short. As described above, if the pulse width of the PWM dimming signal is set to be short, all the light sources included in the light source group are simultaneously turned on in a short time period within one cycle. Consequently, in the display device described in US2012/0230056A, in a case of decreasing the amount of light of the backlight, there is a problem in that flicker occurs in a displayed image of the display device.
Particularly, a display device within the electronic viewfinder device displays an image in a dark environment within a camera main body. Therefore, flicker in the displayed image is more likely to be seen by a photographer, and may cause discomfort to the photographer.